Electrodeposition of rubber



Patented Oct. 21, 1930.

v UNITED STATES PATENT OFFICE wnmrm ARTHUR WILLIAMS, or EDINBURGH, scornann ELEGTBODEPOSITION OF BLUBIBEE' i No Drawing. Application filed ma 12, 1921, Serial No. 190,964, and in Great Britain February 7, 19 27.

V latex and used in conjunction with suitably selected electrodes directly connected together conductively outside the electrolyte, will act as a self-excitant, setting up an electromotive force suflicient to cause deposition of rubber or homologous substances upon the anode element of the circuit, but insuflicient to cause a decomposition which would'produce gas bubbles at the anode.

In the collection of latex on the rubber plantations for export in the latex form, it

is usual to add an alkali such as ammonia for the purpose of preventing premature coagulation.

' For the purpose of my process, it is desirable to reduce this alkalinity in the latex to a minimum, and this is effected by the addition of an electrolyte which not only reduces the alkalinity to the necessary point, but also sets up withthe electrodes a resulting chemical action and electro-motive force in the circuit, whichcauses deposition of the rubber upon the anode element of'the circuit due to the electro-negative character of the rub her or like constituentof the latex.

The electrolyte selected must be such that, when added to the latex, it is not in itself capable of causing coagulation of the latex except after a considerable interval of time, if at all.

ample, as zinc oxide or sulphur, or other vulcanizing agents, with or without accel- Other chemicals or fillers, such for exmight be obtained by immersing conductively connected suitable electrodes in a preserved or alkaline latex without the necessity of adding ammonium chloride or another electro te. As an example of one method of carrying out the invention, to ordinary commercial alkaline rubber latex prepared with ammonia and having an alkalinity corresponding approximately to a semi-normal solution of ammonia, is added ammonium chloride solution until the content of ammonium chloride is approximately twenty per cent by weight, thus at the same time reducing the alkalinity of the mixture to approximately that of a solution of ammonia. The elec- .of the rubber upon the anode.

The deposition of the rubber or like constituent from the latex can be continued until the desired thickness of, rubber or the like has been obtained upon the anode element, which may be shaped to give any desired form to the deposited rubber. The article is then complete in the case of vulcanized latex, and in the case of, ordinary commercial latex it can then be vulcanized, if desired, by-any known method. 1

It is to be understood that the degree of alkalinity of the'mixture of latex and electrolyte will depend upon the nature of the electrolyte.

I do not confine myself to the chemicals, metals or materials herein mentioned or to the proportions or degrees of alkalinity herein stated, these being given only as examples.

Claims: T

1. A process for the electro-deposition of rubber or homologous substances from alkaline latex, which consists in the addition to 100 the latex of an electrolyte which will not in itself readily cause coagulation, but which in conjunction with suitably selected electrodes immersed in the mixture, and directly and conductively connected together externally,

will act as a self-excitant, setting up an elec- V tro-motive force in the circuit sufilcient to effect deposition of the rubber or homologous substances upon the anode element, but insuflicient to cause a decomposition which would produce gas bubbles at the anode. v

2. A process for the electro-deposition of rubber from an alkaline rubber latex which consists in adding to the latex ammonium chloride solution, and introducing into the mixture zincand carbon electrodes directly and conductively connected together outside the mixture,

The foregoing specification signed at Edinburgh, Scotland, this twentiethtday of April, 192

WILLIAM ARTHUR WILLIAMS. 

